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    <title>Document</title>
    <script>
        function countDown(time) {
            var nowTime = +new Date(); //当前的总的毫秒数
            var inputTime = +new Date(time);  //用户输入的总的毫秒数
            var times = (inputTime - nowTime) / 1000; //总的秒数
            var d = parseInt(times / 60 / 60 / 24); //天
            d = d < 10 ? '0' + d : d;
            var h = parseInt(times / 60 / 60 % 24); //时
            h = h < 10 ? '0' + h : h;
            var m = parseInt(times / 60 % 60); //分
            m = m < 10 ? '0' + h : h;
            var s = parseInt(times % 60); //秒
            s = s < 10 ? '0' + s : s;
            return d + '天' + h + '时' + m + '分' + s + '秒';
        }
        console.log(countDown('2021-7-26 12:00:00'));
        var date = new Date();
        console.log(date);
    </script>
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